Lewis acids have been disclosed in U.S. Pat. No. 3,763,217 as being suitable catalysts for reacting an organic carbonate with an aromatic amine to prepare carbamates.
It has been unexpectedly discovered that zinc and divalent tin salts provide the desired carbamates in higher yields and/or selectivity than the particular Lewis acids disclosed by Brill in U.S. Pat. No. 3,763,217.